The invention relates generally to controls for seed planters and, more specifically, to a control element that is manipulated to control the dispensing of seed from a pneumatic seed meter.
In many parts of the world row crops must be planted in a short timeframe to achieve maximum yield. Farmers seeking to expand their cropland must do it without expanding the duration of planting beyond the optimum time period. Because farmers find it more efficient to use a wider planter instead of adding another planter and operator, planter manufacturers have expanded row crop planter widths. However, one undesired condition that gets worse as planter width increases is overlap.
Overlap occurs each time passes of the planter intersect (FIG. 1). Wider planters produce greater overlap because all rows are planting whenever the planter is moving and row units are engaged with the soil. Farmers experience economic loss in overlap areas because seed is wasted and yield is reduced compared to non-overlap areas. Essentially, overlap areas are planted twice or more depending on the number of intersecting passes. Extra plants in overlap areas take soil nutrients and moisture from the intended plants, which results in reduced yield compared to non-overlap areas. Farmers contend with these conditions at end rows, point rows and waterways.
Electric actuated drill shaft clutches are recognized as the first device to reduce overlap on row crop planters. These clutches turn groups or sections of seeding units (called rows) on and off. The planter operator manually turns these clutches on and off when the planter section intersects another pass (FIG. 2) thereby reducing overlap.
Electric drill shaft clutches turn rows on and off by controlling a section of the drill shaft. The drill shaft spans across the planter toolbar and rotates at a speed proportional to the speed of the planter. Row units, each containing a seed meter device, are attached to the planter toolbar. The seed meter of each row is mechanically connected (commonly with a chain) to the drill shaft. Each drill shaft section turns a bank of rows on and off at the same time. The electric clutch turns seeding on and off by mechanically engaging and disengaging the drill shaft section to the planter transmission. Smaller width planters are typically made with one drill shaft section. Larger width planters are commonly made with two to four drill shaft sections to allow for planter folding. Each drill shaft section is fitted with a drill shaft clutch.
Another prior art control apparatus is a pneumatic actuated sprocket clutch that controls each row independently. Pneumatic actuated clutches are electrically controlled by an electric over air valve. The drill shaft must be removed for sprocket clutch installation, repair or replacement.
Electrical current requirements of the electric over air valve are much less compared to an electric drill shaft clutch. Another advantage of sprocket clutches over drill shaft clutches is that the planter can be subdivided into more sections without creating more drill shaft sections. This is beneficial for retrofit installations.
Another prior art apparatus is a pneumatic actuated clutch mounted outside the row unit at the seed meter input shaft. The advantage of this over the sprocket clutch is that installation does not require removal of the drill shaft. A big disadvantage is that the clutch is exposed to flying debris from planter lift wheels.
Initially the planter operator manually turned all the aforementioned clutches or planter sections on and off manually. In practice, most operators find it difficult to do this accurately because the planter is moving and there are other machine functions to monitor and control.
It is known to use an electronic control and GPS system that automatically controls all the aforementioned clutches by mapping planted field areas. The system automatically shuts off clutched planter sections when the sections encounter a planted area. Sections are automatically turned on when they encounter an unplanted area. This represents an improvement in that overlap is consistently minimized and the operator can pay more attention to other machine functions at pass intersections.
Several attempts at controlling pneumatic seed meters are known. U.S. Pat. No. 4,872,785 discloses a shut-off means for air-actuated planter, which includes a butterfly valve located within the air manifold of the planter unit, which is connected to a rotational means further connected to a solenoid. When the butterfly valve is open, air is allowed into the meter, enabling the rotating seed disc to pick up and hold individual seeds in perforated seed pockets until the seed exits the air chamber. Once out of the air chamber, the seed falls off the disc, into the soil. When closed, the butterfly valve blocks the flow of air to the seed meter, which causes all seed held on the disc to fall off and prevents the disc from picking up new seed. When the butterfly valve reopens, the seed disc has to rotate the equivalent of 9-12 feet of planter travel before it starts dispensing seed into the soil again. Turning on air supply 9-12 feet before encountering unplanted area compensates for the delay, but many times is not practical. Making sharp turns on end rows or starting in a corner are a few examples where a 9-12 foot “head start” is not practical.
U.S. Pat. Nos. 4,091,964 and 4,241,849 discloses an air cut-off pad for an air planter, however it does not disclose a pad controlled in any variable way.
U.S. Pat. No. 5,431,117 discloses a seed drum row shutoff for a planter. This patent does not disclose any shut-off means for a rotating seed disc with perforated seed pockets.